Power conversion devices that convert AC power supplied from an AC power supply to DC power and supply the DC power to a DC load are increasingly required to have high efficiency, while power conversion devices for achieving high efficiency are proposed (see, for example, Patent Document 1). A power conversion device disclosed in Patent Document 1 is composed of: a rectification circuit connected to an AC power supply; a smoothing capacitor connected to the rectification circuit; a first switching circuit connected to the rectification circuit via the smoothing capacitor; a transformer provided with a resonance capacitor and a resonance inductor; and a second switching circuit provided on a DC load side with respect to the transformer. In the power conversion device, switching operation of the second switching circuit is controlled, whereby switching loss is reduced and high efficiency is achieved.